Fragile-X mental retardation in a large five-generation family. A clinical and cytogenetic study.
A number of problems concerning both clinical and genetic or cytogenetic aspects of the fragile-X syndrome remain unsolved. In the present work, a large 5-generation fragile-X family has been clinically and cytogenetically investigated. The results of our study indicated that an unusually high proportion of affected males was present in the family examined; all fragile-X-positive males were profoundly retarded and showed the phenotype typically described for this syndrome; moreover, we observed a variability of penetrance within the pedigree and all fragile-X-positive females in the 4th and 5th generation had some degree of mental impairment. A multistep mutation model has been proposed in order to explain some of these findings.
Raimondi
E
E
Dipartimento di Genetica e Microbiologia A. Buzzati Traverso, Università di Pavia, Italia.
Lenti
C
C
Romagnoni
M
M
Negri
R
R
Gambini
E
E
Musetti
L
L
De Carli
L
L
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics*; D006801:Humans; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D012729:Sex Chromosome Aberrations / Q000235:genetics*; D014960:X Chromosome / Q000032:analysis*